This invention pertains generally to multi-point remote audio conferencing, and more particularly to such conferencing utilizing packet data networks.
A hoot n"" holler network is a multi-point four-wire audio conference network that is always xe2x80x98upxe2x80x99. When someone wants to communicate over the network, they push a button and speak either through a microphone, handset, or squawk box. The button does not cause any signaling to occur. It simply enables the audio that is normally disabled to prevent noise from being injected into the network when the person is not speaking.
Hoot n"" holler networks are used throughout the brokerage industry to communicate xe2x80x9cThe Morning Reportxe2x80x9d as well as to advise the trading community within a brokerage firm on market movements, trade executions, and so on. A typical brokerage firm will have several of these networks for equity, retail, bonds, etc., with size and the degree of interactivity varying depending on the application.
The hoot n"" holler system is not specific to the brokerage industry. Many other industries require collaboration on a regular basis. Some of these collaborations can be done via a scheduled conference call, but in problem-solving situations, an ad-hoc conference over a permanent hoot n"" holler network would be more efficient.
Hoot n"" holler networks are typically spread over four to eight sites, although retail networks may have as many as 500 sites interconnected. Within a site, bridging is done locally with a standard audio or digital bridge circuit. Between sites, the bridging is often provided by a phone carrier. The carrier provides dedicated (either analog or digital) four-wire connections into a central bridge. The customer is charged on a monthly basis for the service, with most of that cost attributed to leased-line point-to-point connections between the various sites and the bridge.
FIG. 1 shows an example hoot n"" holler network 20. Conference sets 22 at each remote location are connected to a central bridge 24 via leased lines 26, 28, 30, and 32. Four wire connections and Nxe2x88x921 bridges are used to avoid echo problems (an Nxe2x88x921 bridge mixes up to N possible input signals, but subtracts out each speaker""s contribution individually for the mixed signal being transmitting back to him).
Hoot n"" holler networks are costly, particularly because they require dedicated leased lines for their operation. The present invention provides a packet data solution to an audio conferencing system that replaces the leased lines with data network connections. The typical hoot n"" holler network has less than 15% overall utilizationxe2x80x94as the present invention utilizes data network bandwidth primarily when someone is actually speaking, the present invention can provides significant cost savings, compared to dedicated connections, for the typical hoot n"" holler user.
The present invention does more than merely replace the leased lines of FIG. 1 with packet data connections. The present invention removes the requirement for a central bridging site altogether. Instead, direct connections between conferencing system endpoints are provided xe2x80x9cin-the-cloudxe2x80x9d of the data network, e.g., using multicast packet transmission. When a conference participant speaks, a packetized version of their voice is multicast to all other participants. Transceivers local to each conferencing system endpoint provide speaker arbitration and/or mixing necessary for the system to operate. This system provides several advantages: it allows data network bandwidth reduction by avoiding multiple unicast signals, allows voice compression to be used throughout the conference to further reduce bandwidth, is easily rescaled and reconfigured, and eliminates a portion of the delay inherent in a system requiring communications to-and-from a central site.
In one aspect of the present invention, a distributed packet data network conferencing system is disclosed. This system comprises multiple packet data conferencing transceivers interconnected via a packet data network. Each transceiver is also connected to at least one conferencing endpoint local to that transceiver. The transceiver comprises two data flow pathsxe2x80x94a first path from the local conferencing endpoint to the network, and a second path from the network to the local conferencing endpoint. Each transceiver implements a switchable connection in the first path controlled by an arbitrator within the transceiver.
The conferencing transceivers utilized in the system above comprise a further aspect of the present invention. In particular, the arbitrator contained in each transceiver enables distributed conferencing by providing control over the number of simultaneous talk streams present in the system. Preferably, the arbitrator monitors source attributes of conference data appearing on both data paths. The arbitrator opens the switch to prevent transmission of the local signal when the number of sources of conference data exceeds a preset maximum and the local signal loses an arbitration against the remote sources. The arbitrator may preferably also provide guidance to an input selector inserted in the second data path, allowing it to discard packets from remote sources that have lost arbitration.
In yet another aspect of the present invention, a method for packet data conferencing between multiple remote conference participants is disclosed. The method comprises transmitting each remote conference participant""s voice to other remote conference participants by transmitting a transmit packet data talk stream from a transceiver local to that conference participant to a multicast group address. The method further comprises receiving, at each transceiver local to a remote conference participant, receive packet data talk streams from other remote conference participants sent to the multicast group address. At each transceiver, that transceiver""s transmit packet data talk stream source is ranked against each receive packet data talk stream source. When the total number of packet data talk streams sensed by that transceiver exceeds a preset maximum and the transmit packet data talk stream source ranks lowest, that transceiver inhibits transmission of that transceiver""s transmit packet data talk stream.